The contactless card or non-contact card, as RF (Radio Frequency) card, which integrates the RF (Radio Frequency) identification technology successfully, has solved the problems of no supply power inside the card and non-contact feature. It is a big breakthrough in the electronic parts and components field.
In addition to the features of the contact card, the contactless card has the following features that
1) it is of convenient operation, in which the communication between the contactless card and its reader is wireless, so the user does not need to insert or pull the card, or fix the direction of the card, and all the user needs to do is just swaying the card within the reading area in front of the card reader (generally the valid range is within 5 to 10 cm), while the information stored in the card will be put into the card reader or the corresponding operation command will be executed inside the card, which improves the speed of the operation and is suitable for the place where many cards must be read in a short time;
2) it is of anti-interference performance, in which the conflict prevention mechanism of the contactless card can prevent the data from interference among the cards when they are put within the reading area at the same time, which permits more than one card to operate at the same time;
3) it is of high reliability, in which the contactless card and its reader do not contact each other mechanically, which avoids the troubles caused by mechanical contact, and it is no need to worry about invalidation of the card caused by the broken touch-point as well, so that the reliability of the usability is improved and the life of the card and device is extended;
4) it is of high security, in which the chip of contactless card is a security chip, the operation of the card is protected by a password and the data in the communication process is encrypted, so that all of those guarantee the security of the card; and
5) it is of multiple applications, in which the structure of the contactless card provides one card with multiple functions, so that one card can be used in different systems and places, for example, paying by card for bus transportation fee or other bills, checking the working attendance, or access controlling system, etc.
The advantages above bring many conveniences to the user. With the extension of the application field, the contactless card is more used for payment. And the advantages such as high security of the card are doubted as well. The sequence number of the contactless card is unique and can not be modified; when the contactless card is used, there are three times mutual certification between the contactless card and the card reader and the data in the communication process between them are encrypted; every sector has its own password and access condition. But since the contactless card has such an feature that the information stored on the card can be accessed by the reader by simply placing the card in front of the reader (approximately within a valid range of 5 to 10 cm from the reader), it is possible that the sensitive information of cardholder stored thereon is maliciously utilized by other people with an appropriate reader. As a result, the legitimate cardholder may suffer the loss.
Some contactless cards just execute the corresponding commands internally and do not output the information of the cards when they communicate with the card reader. In this case, if the appropriate card reader is put closer to the contactless card secretly, the contactless card will execute the corresponding command, which will bring the trouble and loss to the cardholder.
The prior solution for overcoming the disadvantages above is that a switch circuit is set on the lead connected the card chip to the antenna coil, by which the cardholder controls the right for outputting the information stored in the card or executing of the corresponding command inside the card. So the privacy of the information stored in the card is protected, the information stored in the card is prevented from being stolen, and the mis-operation to the card is avoided.
But the prior solution is not perfect, and the disadvantages are that when the switch circuit is closed, the continuity of the antenna resonant loop is not good because of the impedance, which is inconvenient for cardholder to operate, and meanwhile, any information output from the contactless card or command executed inside the card is controlled by the cardholder, so that the usability of the contactless card is weakened.